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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 6: Tìm số tự nhiên n, biết: (3.n + 5) ⋮ (n – 3)

Toán Lớp 6: Tìm số tự nhiên n, biết:
(3.n + 5) ⋮ (n – 3)

Comments ( 1 )

  1. 3n + 5 \vdots n – 3
    => 3n – 9 + 14 \vdots n – 3
    => 3( n – 3) + 14 \vdots n – 3
    Vì 3(n – 3) \vdots x – 3 nên 14 \vdots n – 3
    => n – 3 in Ư{14} = {± 1 ; ± 2 ; ± 7 ; ± 14}
    => n ∈ {4 ; 2 ; 5 ; 1 ; 19 ; – 4 ; 17 ; – 11}
    Vậy n ∈ {4 ; 2 ; 5 ; 1 ; 19 ; – 4 ; 17 ; – 11} thì 3n + 5 \vdots n – 3

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222-9+11+12:2*14+14 = ? ( )